(i) Field of the Invention
The present invention relates to a scroll fluid machine and, more particularly, to a scroll fluid machine for lubricating an orbiting bearing with grease.
(ii) Description of the Related Art
JP-A No. 2004-340255 discloses a structure of an orbiting-bearing oil seal of a scroll compressor that includes an L-shaped cross-section and annular sealing member provided in the oil seal and having a breathing hole formed therein for a flow of outside air into the inside of the orbiting bearing housing.
JP-A No. H08-254213 discloses a water-pump bearing hermetic structure in which an oil seal having a plurality of seal lips (lip seals) is placed in a dividing area between water and a lubricant oil and a groove or projection is provided in the seal lip to prevent leakage of the water or lubricant.
JP-U No. S62-096166 discloses an oil seal that includes a lip having an annular sliding surface on which a plurality of first protrusions are inclined uniformly along the axis and a plurality of second protrusions inclined opposite to the inclined direction of the first protrusions along the axis in order to use the pumping action of the protrusions to discharge oil flowing on the sliding surface of the lip toward the bearing so that the dust flowing onto the sliding surface of the lip from the atmosphere is discharged back to the atmosphere.
JP-A No. 2004-340255 has a risk of leakage of the lubricant from the lip seal due to increased pressure in the orbiting bearing housing if the breathing hole is clogged with the lubricant.
In JP-A No. H08-254213, the hermetically enclosed space is defined by the seal lips of the oil seal provided on both sides of the sealing device of the bearing. This poses a risk of stepwise leakage of a lubricant from the seal lip if the internal pressure in the sealing device of the bearing is increased due to an increase in temperature of the bearing or the like during the operation of the water pump.
In JP-U No. S62-096166, because the first protrusions and the second protrusions are placed in contact with the shaft so as to be disconnected, a hermetically enclosed space is created in the orbiting bearing housing when the oil seal is used for orbiting bearing in a scroll compressor. JP-U No. S62-096166 has a risk of stepwise leakage of a lubricant from the lip if the internal pressure in the sealing device of the bearing is increased due to an increase in temperature of the bearing or the like.